I. Field of the Invention
The present invention relates to disposable lancet devices used to create an incision in the skin of a patient, through which a blood sample can be obtained. More particularly, the present invention relates to low cost lancet devices that are easy and inexpensive to both manufacture and assemble.
II. Statement of the Prior Art
Blood samples are drawn routinely from patients for use in numerous types of blood tests. The blood needed for many tests is conventionally drawn by creating a small incision in the patient's skin. Typically, such incisions are made on the patient's fingertip, However, with patients such as neonates or persons with poor circulation, the incision can be made in alternate areas such as the foot, arm or leg. Typically, the device used to create the needed incision in the patient is a mechanical lancet device. Such lancet devices conventionally employ a cutting blade spring loaded within a housing. The housing is placed against a patient's skin and the blade is released. The potential energy stored within the spring bias of the blade then causes the blade to exit the housing and to create the needed incision in the patient's skin. The advantage of such mechanical lancet devices is that uniform incisions can be made providing good control over the location, depth and sterility of the incision. Furthermore, such mechanical lancet devices often prevent the patient from seeing the often unsettling scene of his or her skin actually being cut.
In the development of the art for mechanical lancet devices, many different designs have been created. The most modern of the designs typically are disposable, having retractable blades and other operations that prevent their reuse after a single incision has been made. Another common feature to many prior art lancet devices is that they make incisions using a plunge cut, that is the cutting blade is plunged through the skin traveling perpendicular to the skin and the size of the incision matches the size of the cutting blade. Such prior art lancets are exemplified by U.S. Pat. No. 5,133,730 issued on Jul. 28, 1992 to Biro, entitled DISPOSABLE RETRACTABLE FINGER STICK DEVICE AND METHOD FOR MAKING THE SAME and assigned to International Technidyne Corporation the assignee herein. In the Biro patent, a sharp blade on a pivot arm is spring biased to move out of, and then reenter, a housing via an orifice in the housing. Although the blade is positioned on a pivot arm, the blade is directed into the skin of the patient relatively perpendicular to the surface of the skin. The shape of the blade helps the blade enter the skin and make the needed incision.
Other lancet devices that create a plunge cut are exemplified by U.S. Pat. No. 3,760,809 to Cambell, Jr. entitled SURGICAL LANCET HAVING CASING and U.S. Pat. No. 5,395,388 to Schrage, entitled SINGLE UNIT LANCET DEVICE. Since lancet devices are typically designed to be disposable after one use, it will be understood that the manufacturer with the lowest unit price would have an advantage over competitors. Consequently, manufactures have been motivated to design disposable lancets with simpler designs that can be made less expensively. In response to such design efforts, manufactures have developed lancets with only two or three separate parts. In such devices a cutting blade is held by a complex molded structure that both advances and retracts the blade. Such prior art is exemplified by U.S. Pat. No. 4,553,541 to Burns, entitled AUTOMATIC RETRACTABLE LANCET ASSEMBLY, and U.S. Pat. No. 5,212,879 to Biro et al., entitled METHOD FOR MANUFACTURING A DISPOSABLE-RETRACTABLE FINGER STICK DEVICE, which is assigned to International Technidyne Corp., the assignee herein. Although such devices have far less parts than some prior art lancet devices, they are no less complex. Accordingly, the tools needed to mold the primary lancet structure is highly complex and the parts produced must be maintained at high tolerances. This produces a large amount of reject parts and significant downtime as the molding tool is cleaned and maintained. All this work adds to the cost of the lancet device and makes it difficult to consistently produce a high quality product.
In many prior art lancet devices, expensive metal springs are used, wherein the cutting blade is either part of the spring or is driven by the spring. The use of springs adds significantly to the cost of the overall lancet as well to the complexity of assembling the lancet with the spring being in its compressed, ready-to-use orientation.
It is therefore an object of the present invention to provide a lancet device that does not use a metal spring.
It is a further object of the present invention to provide a disposable lancet that is relatively inexpensive to manufacture and not requiring complex and molded parts.